


assumptions make an ass

by kettish



Category: Voltron: Legendary Defender
Genre: Alien Biology, Anal Sex, M/M, Virgin Kink
Language: English
Status: Completed
Published: 2020-02-29
Updated: 2020-02-29
Packaged: 2021-02-28 04:27:02
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,183
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22947757
Author URL: https://archiveofourown.org/users/kettish/pseuds/kettish
Summary: Shiro knows Keith has probably never been with anyone before, so he takes it slow.
Relationships: Keith/Shiro (Voltron)
Comments: 15
Kudos: 213





	assumptions make an ass

**Author's Note:**

> For a_no_ba for Sheithlentines! <3 Sorry I made you wait. I had another fic in mind and halfway done before realizing it needed serious overhauling and had to start over. XD

Shiro has been in heaven since he started dating Keith. The man is lean, beautiful, strong as steel cording and with the kind of slim muscle that Shiro has always secretly wished for and that he finds desperately attractive. The icing on the cake is that he’s let his hair grow long, and ties it back and up, and all Shiro can think about is letting it down and gripping it tight while fucking into his mouth. With or without hair, though, he’s still Keith: loyal, confident, intelligent, with sharper instincts than anyone Shiro has ever known and an adrenaline addiction that surpasses Shiro’s own.

It’s going to be delicious when Shiro doesn’t have to ease Keith into things, but for now, he’s holding back. He’s pretty sure Keith has never been in a relationship before--he’d never mentioned dating anyone, anyway--and he’s even more certain that Keith is a virgin. He was so shy when they first kissed, hesitant and whisper-gentle, barely touching before Shiro encouraged him to let loose and go a little harder, use his tongue, use his teeth. Keith took to kissing like he took to everything physical: with alacrity and enthusiasm.

Since then Shiro has been slowly letting them progress a little further each time they have together. There will be a few days where they have no privacy, and they just sit and relax with each other on the couch with the other paladins, hands laced politely even as Shiro is itching to lay Keith back down against the cushions and ride him until he forgets how to talk. Soon, Shiro vows. (Prays.) But first he’s probably going to have to top at least the first time, to show Keith how. (Shiro’s first time had been like that, and his partner said it was the norm.) If he’s lucky Keith will at least trade off with him after that.

Keith is making it really difficult to hold back, though. Between the sultry looks he gives Shiro across the desk, the way he flirts his hips a little on his way out the door, and the way he’s started to be a little more aggressive in their makeout sessions, Shiro is ready to implode if he doesn’t get to at least suck his dick sometime soon. Please, please let him suck his dick, he prays. He hasn’t been able to see it yet but he’s felt it when they grind a little and it’s a good size.

It’s during one such grinding session where things come to a head. Keith doesn’t seem to want to stop, and Shiro is so close to cumming that his eyes are trying to cross, and Keith has him on his back on the couch, pressing him down and rutting against him like he owns him. It’s one of the hottest things Shiro has ever seen and he loves this man so much holy shit.

They get really hot and heavy, and wow Keith is really getting into it, and it makes Shiro melt into the couch to be honest--he’s always preferred bottoming, loves being able to lay back and accept pleasure and force, so this is really doing it for him. Keith’s rolling his hips down against Shiro and Shiro’s grabbing his ass to urge him to do more, harder, when Keith pulls back.

“You ok?” asks Shiro, worried suddenly that it had been too much. Keith grins and shakes his head.

“Absolutely. Want to go to your bedroom though? More space.” Shiro grins back in response and then finds himself being hauled up and pushed along down the hall, then pushed back onto the bed, comforter soft around him.

“Keith, if you want to--”

“I can do whatever,” Keith says immediately, and Shiro feels so in love with this giving, brave man. He doesn’t even know what Shiro was going to ask and he’s already agreeing.

“Okay,” Shiro agrees, “Lube’s in the drawer, if you want to give it to me.” Keith’s face brightens and heats simultaneously and they both take a moment to shove their clothes off before Shiro hears the drawer slam and he’s bowled back over again, Keith hovering over him and kissing him within an inch of his life.

Finally pressed skin to skin, their cocks bump and slide against each other. Shiro hears the lube being opened. He can’t figure out why Keith’s opening it when he asked for Keith to hand it to him--and then there’s gentle fingers circling his hole, making him jump and moan in surprise, dipping in carefully and oh! That's Keith, smirking at him for just a moment before they’re kissing again.

Keith is gentle and firm and making sure Shiro is feeling good and ok, Shiro’s a little lost. Maybe uh...maybe Keith has done this to himself? Obviously he misunderstood that Shiro was offering to top, but Shiro is absolutely on board with being fucked so he doesn’t object. They can figure it out. Shiro can coach him. 

Then Keith finds his prostate and is stroking it, and stretching him, then stroking, then spreading lube again...the rhythm is random and agonizingly pleasurable. He’s lucky he has the world’s most talented virgin for his boyfriend and oh god ok that’s--that's amazing, honestly, and--no, wait, why is he pulling his fingers out?

“Still good?” Keith asks, concerned, and Shiro wheezes out a mildly hysterical laugh.

“Oh yeah,” he pants, “I’m good. I’m very good. Super good.” Keith preens for a second before pouring a little more lube onto his fingers and slicking himself up, and Shiro finally gets to see his boyfriends erection for the first time. It’s thick, but not ridiculously so like Shiro’s cock is, and it looks perfect for sitting on; Shiro vows to make that happen sometime soon. Very soon.

“Ready?” Keith asks, and Shiro grins again in reply. His cheeks hurt a little from smiling so much but it’s so worth it.

Keith presses in slow and steady and groans, low and deep in his chest. Shiro pets his face, his hair, his shoulders, everywhere he can reach, and Keith waits. Shiro sympathizes; his first time, he blew his load two strokes in and was eternally shamed. Keith seems to be doing well though, still and patient. The minute stretches, becomes two, and Shiro frowns.

“Are you ok?” he asks, and Keith blinks.

“Yes, I was waiting on you.”

“I'm good baby, you didn’t have to wait,” Shiro says with a dopey, love-struck smile. Keith laughs and then pulls out a little, pushes back in. He increases the length of his strokes in increments, and Shiro is beyond impressed with his unbelievably good control at this point. It’s not long before Keith’s smacking up against Shiro's ass with each thrust, and Shiro loves life, the universe is good, holy  _ shit yes _ \--he yelps when Keith pegs his prostate. Keith notices immediately and with a feral grin hauls Shiro’s ass up into the air, pulls his legs over his shoulders, and starts railing him like a fucking porn star, nailing the spot with at minimum every third stroke. Shiro gasps and hiccups and moans and  _ wails _ and Keith barks an absolutely joyful laugh as he goes faster. 

Its insane, its fantastic, its so fucking good Shiro is going to lose his mind. He gets a hand on his cock and starts jerking himself like it’s a race--then he comes, quicker than he has in years, his orgasm taking him like a flash flood and tumbling him along before leaving him gasping afterwards.

Keith slows, grinding into him to draw it out, and then stops when its apparent Shiro’s getting oversensitive. Shiro just gasps for air, his chest heaving like he's sprinted a five minute mile, so Keith lowers himself down to gently lay against Shiro, anchoring him. 

“Oh my god,” Shiro finally manages. “Oh, my god.” Keith smiles and presses kisses to his jaw; the way the movement pushes Keith’s cock in further reminds Shiro that Keith still hasn’t come yet.

“You always beat me,” Shiro laughs. “My first time I lasted thirty seconds. I definitely didn't blow my partner’s mind.” 

Silence. 

“This isn’t my first time,” Keith says slowly. Shiro's jaw drops and he feels like he should say something but nothing comes out. Keith’s mouth twists to the side in concealed amusement before he continues, “Shiro, I'm twenty-two. I worked with the Blades starting when I was eighteen. I have had a lot of sex.” 

Shiro shifts his gaze to stare at the ceiling blankly as he tries to process the fact that Keith might actually be the more experienced partner here 

“You thought,” Keith says in a richly amused voice, and abruptly he pushes in a little more, making Shiro wheeze, “that I was doing all this on  _ accident _ ?” His dick pushes a little bit against Shiro’s prostate again and it doesn’t hurt by now, it’s just a little sensitive, and oh. Okay, that feels nice. Keith moves a little at a time, like when he first started, increasing speed and force bit by bit until Shiro’s dick is completely hard again and Shiro’s making little hiccuping gasps with each thrust. Fuck, how had he thought Keith had never done this before?

“You really thought,” Keith leans in to murmur lowly, nibbling at his neck, “that I made you cum so hard you blacked out because, what--I have good instincts?” He snaps his hips in hard. Shiro yelps, and Keith laughs.

“No,” he says, and Shiro can’t look away from how his eyes have gone dark, the confident smirk on his lips, the liquid way his shoulders and arms flex and pull with each thrust. “Sweetheart, I know how to  _ fuck _ .” 

With that he wraps Shiro’s legs around his waist, plants his hands on either side of Shiro’s chest, and proceeds to destroy him. Shiro can’t stop making noise, crying out, making embarrassingly high pitched  _ ah-ah-ah _ ! sounds; he can’t believe how badly he misjudged, but more, he can’t believe how fucking hot it is that Keith is taking him to pieces like he was born for it. His hole is filthy wet with lube and there’s cum drying on his stomach from his first orgasm, and Shiro has never been a multiple orgasms kind if guy, but he can feel it coming on. There's a tightness in his lower back creeping down to his balls, the pleasure from how Keith hammers into him combining with the way his own dick is bouncing against his stomach and rubbing against Keith’s stomach. Keith keeps going, his eyes blazing and pinning Shiro where he is as he makes him feel like he’s taking him apart and putting him back together how he likes.

“Oh fuck, gonna--oh, fuck, Keith, I--” He can’t even finish the sentence, isn’t sure why he said anything, all he wants is to cum--it’s right there, he can feel it--fuck, fuck! Keith’s eyes sharpen as he shifts his weight just a bit, and brings a hand up to pinch Shiro’s nipple, and that’s it, that’s done it. Shiro cums so hard he curls up and forward, legs tightening to keep Keith where he’s seated deep in Shiro's ass. He shoots far enough up his chest that Keith could bend and lick it off of him, and Keith presses in deep, cumming just as hard. He feels enormous, and fucks his cum in as far as it’ll go. Shiro can’t help but whine when Keith finally stops. 

They’re both panting this time, and Shiro is definitely going to feel this tomorrow, but all the prep beforehand did it’s job; he isn't in any real pain. Keith sighs, content, and settles down on top of Shiro without pulling out. Shiro allows it, treasures spending a little time still connected physically to Keith without the press of arousal hurrying them along. 

After a few minutes of contented sighs and little shivers on Keith’s part though he really wants to go clean up so they can come back to bed and cuddle.

“Come on, let’s get a quick shower,” Shiro whispers, and Keith snorts awake, apparently having been dozing. It startles Shiro into clenching a little, and Keith gasps, his hips jerking forward a little and pushing in further. Shiro stares, feels a slight throbbing in his ass, and wonders aloud, “Did you just cum again?”

“Yeah?” Keith says distractedly and lets out a shuddering exhale. “Phew. Sorry, surprised me. We can get cleaned up in just a bit once I pull out.”

“Okay, so pull out,” Shiro says. Keith stares at him, brows pulling low with a frown.

“It can’t have been more than ten minutes, tops. I’ll need at least another five.”

“Or you can just do it now,” Shiro says, and all right, he’s starting to lose his patience. Is this some kink Keith forgot to mention or…?

“I can't,” Keith says. He looks a little stressed, a little worried. It’s enough to make Shiro rein himself in and be patient; Keith obviously isn’t being weird on purpose. “It doesn’t go down that fast. I thought it took most guys at least fifteen, how long does it take you?”

“What?”

“Your knot,” Keith asks, “how long does it take to go down?”

Shiro is genuinely shocked into silence.

Then: “my  _ what _ ?”

More silence.

“Your knot?” Keith tries. “You know, the...at the base of your dick? It gets bigger when you get off?”

“I don’t have that,” Shiro says. “Wait, what do you mean you can't pull out?” He moves, wriggles, and panics for a split second when he realizes Keith is stuck in him. “Keith what’s--”

“Nonono don’t move!” Keith yelps, strangled, and yanks Shiro’s hips back flush against his with an iron grip. “It’ll go down in just a minute, I swear, but it’ll hurt if you try and pull off. Just trust me, Shiro, I swear, I thought--I thought it was normal. The Blades almost all have one.” 

“Almost all?” Shiro asks, gaping, as he stills. He trusts Keith, with his life as well as his body, so he calms his racing heart and relaxes his body as well as he can. Keith’s forehead drops down to Shiro’s chest but Shiro catches sight of the rampant flush spreading across his face.

“I didn’t sleep with that many of them,” Keith mutters. “They have communal showers to save space. I’m not some kind of, of--space slut.”

Shiro chokes and then cracks up, laughs deep from his belly, and there’s a strange sensation before Keith’s dick finally slides free with a tiny audible pop and a veritable flood of wetness. Shiro flinches and twists to see underneath him and can’t decide if the volume of the fluid makes him horny or disgusted. Probably would be “horny” when he isn’t immediately postcoital. Then he starts giggling again.

“Space slut,” Shiro snickers, flopping back down and laughing, and Keith huffs loudly, groans in protest, and tries to roll off the bed to escape Shiro’s amusement. Shiro grabs him, ignoring the further gush from his own ass, and holds him where he can rub his chin and cheek against Keith’s hair and face obnoxiously, peppering Keith with kisses between giggles. "Keith, what the fuck."

“It isn’t that funny,” Keith grumbles, but he’s chuckling too. He cups Shiro’s face with both hands and leans in to kiss him sweet and slow; they both sigh and relax, Shiro’s giggles tapering off into contented silence.

“It kind of is though,” Shiro argues after a while, and Keith snorts. With a final kiss, he backs up off of Shiro and this time Shiro allows it without protest, accepting a hand up to head to the bathroom.

“I can’t believe you thought I was a virgin,” Keith grumbles as they wait for the water to warm, Shiro pressed up against Keith’s back while Keith tests the water with one hand. Shiro shrugs.

“You never mentioned sleeping with anyone,” he says. Keith’s frown is barely visible from Shiro’s angle.

“I didn’t feel like telling the man I love that I was sleeping around because I knew I was never going to be with him, so I figured I may as well have sex with friends,” Keith says finally. “I was lonely, and I was eighteen. There were a surprising number of volunteers.”

“Surprising?” Shiro says with a disbelieving laugh. “You’re gorgeous, baby, of course there were volunteers. You may recall I am one of them.” Keith laughs.

“I won’t argue, since I want you to like how I look, but I disagree,” Keith says, and pulls the shower curtain aside. He steps in, just letting the water hit his feet to be sure that it’s really warm, and then steps in fully so that the water is beating against his back.

“C’mon, let me clean off first,” Shiro complains, “you came a gallon in my ass and it’s everywhere.” Keith goes bright red, nods jerkily, and switches spots with him. 

“So what’s this knot thing?” Shiro asks, leaning down with soapy hands to clean the back of his thighs. Keith shifts back a little to keep from bumping him in the face with his dick and lifts it forward to show him. There’s a plump area at the base of his cock which doesn’t look big enough to keep him stuck inside anything, but Shiro assumes it’s erectile tissue like the rest of his penis. 

“So it only expands when you orgasm?” he asks, curious, and reaches forward to thumb at it gently, mindful of postcoital sensitivity. Keith’s dick twitches, and Shiro grins, looking up at Keith to waggle his eyebrows. 

“Shut up,” Keith grumbles, “and yeah. It expands during orgasm and goes down once it’s all finished up.” Shiro’s eyebrows stop waggling and rocket up his forehead.

“Once it’s finished up?” he repeats, “You mean it was--you were cumming the whole time it was stuck inside me?” Keith shrugs, looking more and more uncomfortable.

“Yeah,” he mumbles, and steps back so that Shiro isn’t touching him anymore. The soap he reaches for is standard issue for the Garrison and free for service members, which is why Shiro has it, and Keith uses it to start cleaning himself up as well. 

“I didn’t mean to make you feel weird,” Shiro apologizes after long moments pass in which they both wash, the sound of the shower making the silence more easily bearable. “It’s just different from me and I was curious.”

“I’d wondered,” Keith mutters. “Your orgasm seemed short.” Shiro snorts.

“No, that was normal. I mean, it was definitely a great orgasm, but not abnormal,” he says. “And uh, no knot here. That’s not a 100% human thing.”

“Thanks, Mom,” Keith sighs, and then wrinkles his nose. “Ew. Never mind. Forget I said that.”

“Sure thing, space slut,” Shiro teases. It’s worth the smack to his arm for the way it makes Keith sputter and smile, and for the kiss he accepts afterwards. 

It’s all, every bit, worth it.


End file.
